Real-time monitoring of hybrid laser arc welding

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Laser welding plays an important role in the automated manufacturing of products ranging from cars to pacemakers, but defects can lead to component failure with potentially catastrophic results. Considerable manpower resources must be employed for post-processing quality assurance. By incorporating a novel high speed inline diagnostic system, we can measure weld penetration depth on-the-fly during the welding process with micron precision and at high speeds (>300 kHz). The novel technique, inline coherent imaging, is able to image along the welding beam line, even in the presence of intense optical backscatter. Information is obtained from the welding region itself and can be used to provide feedback to close the control loop to allow desired welding performance with no user intervention, thus reducing the need for post-analysis testing (and dramatically reducing manpower requirements) while improving weld quality. Of potentially even more important consequence, the inline coherent imaging system may allow a new paradigm of welding - hybrid laser arc welding - to be broadly adopted. This new welding technique (described as "the most disruptive in a generation") combines the depth of penetration and low heat input of laser beam welding with the high efficiency of arc welding, but potential clients tell us that uncertainty about penetration depth have slowed adoption in many market segments. A real-time depth measurement system could help certification of hybrid laser arc welding for a variety of industries including petro-chemical, nuclear and defense. NSERC I2I funding will allow us to develop a portable inline coherent imaging system appropriate for integration with commercial welding systems. High-speed digital processing using a dedicated hardware controller will allow real-time feedback to close the control loop. Successful demonstration in a welding company applications laboratory will be used to attract a Canadian company to produce the final commercial product (based on our prototype) and sell it to end users around the world.